The present invention is directed to a shock limiter system for a head suspension in a rigid disk drive, and in particular, to a head suspension having a shock limiter formed in the portion of the load beam or the flexure positioned to engage with an external structure.
In a dynamic rigid disk storage device, a rotating disk is employed to store information. Rigid disk storage devices typically include a frame to provide attachment points and orientation for other components, and a spindle motor mounted to the frame for rotating the disk. A read/write head is formed on a xe2x80x9chead sliderxe2x80x9d for writing and reading data to and from the disk surface. The head slider is supported and properly oriented in relationship to the disk by a head suspension that provides both the force and compliance necessary for proper head slider operation. As the disk in the storage device rotates beneath the head slider and head suspension, the air above the disk also rotates, thus creating an air bearing which acts with an aerodynamic design of the head slider to create a lift force on the head slider. The lift force is counteracted by a spring force of the head suspension, thus positioning the head slider at a desired height and alignment above the disk that is referred to as the xe2x80x9cfly height.xe2x80x9d
Head suspensions for rigid disk drives include a load beam and a flexure. The load beam includes a mounting region at its proximal end for mounting the head suspension to an actuator of the disk drive, a rigid region, and a spring region between the mounting region and the rigid region for providing a spring force to counteract the aerodynamic lift force generated on the head slider during the drive operation as described above. The flexure typically includes a gimbal region having a slider-mounting surface where the head slider is mounted. The gimbal region is resiliently moveable with respect to the remainder of the flexure in response to the aerodynamic forces generated by the air bearing. The gimbal region permits the head slider to move in pitch and roll directions and to follow disk surface fluctuations.
In one type of head suspension the flexure is formed as a separate piece having a load beam-mounting region that is rigidly mounted to the distal end of the load beam using conventional methods such as spot welds. Head suspensions of this type typically include a load point dimple formed in either the load beam or the gimbal region of the flexure. The load point dimple transfers portions of the load generated by the spring region of the load beam to the flexure, provides clearance between the flexure and the load beam, and serves as a point about which the head slider can gimbal in pitch and roll directions to follow fluctuations in the disk surface.
The actuator arm is coupled to an electromechanical actuator that operates within a negative feedback, closed-loop servo system. The actuator moves the data head radially over the disk surface for track seek operations and holds the transducer directly over a track on the disk surface for track following operations.
In prior drives, when shock forces are imparted on the drives, moments are induced on both the actuator arms and on the disks themselves causing the actuator arms and the disks to deflect and move relative to one another. If the forces are great enough, the actuator arm, or baseplate, comes into contact with the disk surface. Such contact is highly detrimental to the disk surface and can destroy large portions of the disk surface rendering those portions unfit for operation. Even with smaller shocks, head slap can be induced in the disk drive. Head slap occurs when a shock separates the read/write head from the disk and the return force causes the read/write head to crash into the disk surface, potentially destroying portions of the disk surface.
One option for addressing this problem includes making the actuator arms stiffer by making them thicker. This solution requires more room in the axial direction and may result in the loss of a disk or a disk surface in the disk drive, thus sacrificing storage capacity.
U.S. Pat. No. 5,926,347 (Kouhei et al.) discloses a mechanism for preventing the magnetic head from being spaced away from the face of the magnetic disk medium when the magnetic disk medium is in the stopped or parked condition. The device of Kouhei does not limit movement of the magnetic head when the disk drive is in operation.
U.S. Pat. No. 5,808,837 discloses a system for limiting the deflection of the load beam during a shock event, including a separate cantilevered element that extends away from the mounting region towards the flexure. In this design, the length of the cantilevered portion of the cantilevered element is very short in comparison to the length of the load beam. Therefore, the amount of slider lift-off cannot be tightly controlled with current manufacturing tolerances. In addition, this approach requires the manufacturing and assembly of an additional component. The device of JP 11-66766 suffers from the same shortcomings.
U.S. Pat. No. 5,831,793 (Resch) discloses a cantilever leaf spring located in the radius region of the load beam that is formed towards the disk surface. The leaf spring is designed to rub on the disk surface just prior to base plate-to-disk impact. The leaf spring decelerates the suspension assembly, but does not limit the slider-to-disk separation or impact velocity. That is, the device of Resch limits the movement of the suspension assembly toward the disk, but does not address slider separation from the disk surface.
A need still exists, however, for an improved head suspension including a mechanism capable of limiting motion of the suspension during disk operation away from the surface of the disk due to impact and shock loading. Such a mechanism should work within the requirements of hard disk drive suspensions, including overall weight limitations, height limitations, manufacturability and functionality.
The present invention meets the ongoing need for improved head suspensions by providing a head suspension with a shock limiter that limits slider lift-off of head suspensions during operation of the rigid disk drive and/or when the head suspensions are parked. The shock limiter can be located in the rigid region or on the flexure (referred to collectively as the distal region). The shock limiter extends away from the head suspension in a direction opposite from the direction of the head slider. The shock limiter is configured to engage with an exterior structure separate from the head suspension. The exterior structure can be a portion of an actuator arm, a portion of the disk drive housing, a back-to-back head suspension or other structures separate from the head suspension.
In one embodiment, the shock limiter system for a head suspension is configured to engage with an external structure in a rigid disk drive. The head suspension has a flexure with a head slider oriented in a first direction over a disk surface. The head suspension includes a load beam having a mounting region, a rigid region and a spring region located between the mounting region and rigid region. The rigid region and the flexure define a distal region of the head suspension. The shock limiter system comprises a shock limiter extending from the distal region in a second direction generally opposite the first direction. The shock limiter is positioned on the distal region to engage with the external structure to limit movement of the head suspension away from the disk surface during a shock event.
In another embodiment, the shock limiter system comprises a shock limiter extending from the distal region in a second direction generally opposite the first direction and an external structure located opposite the shock limiter. The external structure is positioned to limit movement of the head suspension away from the disk surface during a shock event.
In yet another embodiment, the shock limiter system is configured for first and second back-to-back head suspensions in a head stack assembly. The head suspensions have first and second flexures supporting first and second head sliders over first and second disk surfaces in a rigid disk drive, respectively. The first and second head suspensions each include a load beam having a mounting region, a rigid region and a spring region located between the mounting region and rigid region. The first rigid region and the first flexure define a first distal region. The shock limiter system comprises a first shock limiter formed in the first distal region. The first shock limiter extends toward the second head suspension and limits movement of the first and second head suspensions away from the first and second disk surfaces during a shock event.
The shock limiter system for the back-to-back head suspensions may optionally include a second shock limiter formed in the second distal region. The second shock limiter extends toward the first head suspension. The first and second shock limiters preferably cooperate to limit movement of the first and second head suspensions away from the first and second disk surfaces during a shock event.
In the various embodiments, the shock limiter may be located on the rigid region or the flexure. The shock limiter may be integrally formed with the rigid region or the flexure. The shock limiter may have a curved structure and/or a tip configured to engage with the external structure. In one embodiment, the shock limiter has a tip adjacent to the head slider. In another embodiment, the shock limiter is a spring member. The shock limiter preferably limits movement of the suspension away from the disk surface when the head suspensions are parked or during operation of the rigid disk drive.